Iowa City , Iowa -LRB- CNN -RRB- -- Katherine Valde is ready when a fellow student says `` no thanks '' to early voting because of the thrill of casting a ballot on Election Day .

`` Things come up , you can have an exam , '' says Valde , the president of the University of Iowa Democrats .

`` You can wait until Election Day and not know where your precinct is . A lot of students have to go to elementary schools around town , and they do n't have cars , they do n't really know where it is . ''

Truth is , Valde knows younger voters like herself are less reliable when it comes to turning out in the crunch , and `` with early voting , it just gives us 40 more chances to catch people . ''

Valde led by example Thursday , waiting in line for more than an hour to cast her ballot on the first day of in-person early voting in Iowa .

The line at the Iowa City Public Library was dominated by Obama voters , as was a Des Moines polling place CNN visited as the doors opened Thursday .

Valde says the Obama campaign and state Democratic Party have urged her to keep checking her list and pushing students to vote now .

`` If you vote early , it frees up campaign resources to talk to people who might be undecided , '' she told us as she waited patiently to vote .

Iowa is one of 35 states plus the District of Columbia that allow some form of early in-person voting . Of the nine presidential battlegrounds CNN now rates as tossups , only New Hampshire and Virginia do not have large-scale early voting .

In voting , the early bird skips the line

In Iowa four years ago , early voting accounted for 36 % of the ballots cast for president . In Johnson County , home of the University of Iowa , it was 55 % , the highest of Iowa 's 99 counties , and County Auditor Tom Slockett says demand for early ballots so far is up significantly from 2008 .

Key states voting early

And Democrats have a big early edge .

In Johnson County , requests for mail-in ballots as of Monday were running more than 12-1 in favor of Democrats . Statewide , as of close of business Wednesday , the Iowa Secretary of State 's office said Democrats had a nearly 5-1 edge in making requests for absentee ballots .

Republicans here do n't dispute the early Democratic advantage in ballot requests . But they promise to narrow the edge somewhat ; the GOP 's first mailing nudging Republicans to consider mail-in voting was sent just this week .

Iowa Republicans also suggest too much can be made of the early numbers , making the case that those voting before the presidential debates are hardcore partisans who were almost certain to vote eventually anyway .

`` If you look at who is early-voting right now , absentee ballots , 80 % , almost 90 % , are ` four of four ' voters , meaning they voted in the last four elections , '' veteran Iowa GOP strategist Steve Grubbs told CNN .

`` So it 's a difference of strategy . You put your money into the last three weeks or you put your money into early voting . The Republican Party will put a little more into the last three weeks , and the Democrats a little more into the first initial blast of early voting . ''

Grubbs said one effort in which Democrats were smart to focus so much early voting attention was younger voters .

`` Four years ago there was a lot of enthusiasm among younger voters and everybody knows that has lessened , '' Grubbs said . `` They have got to figure out the strategy to increase their early voting . ''

Polls : Obama leads in New Hampshire , tight race in Nevada , North Carolina

On the flip side , he said Republican Mitt Romney runs stronger among the state 's elderly voters , who are among the most reliable to cast ballots .

More broadly , Grubbs conceded a modest Obama edge in Iowa at the moment and said there is nervous talk among some Republicans that Romney could hurt GOP candidates in competitive congressional and other races . In his view , such talk is premature .

`` Clearly if a -LRB- presidential -RRB- candidate loses by more than five , it starts to affect down-ballot and that 's a big issue for Republicans , '' Grubbs said . `` The way I look at it , we are starting the fourth quarter . We have a strong quarterback . And anyone who knows football knows the fourth quarter is where most of the action happens . So October will be big ; and if Romney has a good start to the month , we will be fine . ''

Iowa Republicans also say , despite the Democratic edge in early voting so far , that the GOP is breaking records in terms of its grassroots organizing .

At a Linn County phone bank in Cedar Rapids , volunteer Karen Zmoos -LRB- pronounced Smoose -RRB- is credited with making the millionth voter call in Iowa this cycle .

She is pleasantly working the phones again this week , and adding this question when a voter indicates support for the Romney-Ryan ticket : `` Excellent . Would you be interested in voting early this election ? ''

Zmoos says Iowa 's unpredictable winters make her a fan of early and absentee voting , and she shrugs off the early Democratic edge in absentee ballot requests as temporary .

`` You know we are working hard here , '' Zmoos said during a quick break from working the phones . `` We are rolling up our sleeves and putting our boots on , and we are going at it . We still have time . ''

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Iowa is first battleground state to open early voting and one of 35 states that allow it

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Democrats have edge in those voting early , but Republicans downplay importance

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Iowa Republicans say they 'll put their efforts into last three weeks before Election Day

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Iowa GOP concedes Dems ' early voting efforts but claims records in grassroots organizing